import random
import datetime
def code():
    ret =' '
    for i in range(4):
        num = random.randrange(0,9)
        zimu = chr(random.randint(64,121))
        s = str(random.choice([num,zimu]))
        ret += s
    print(ret)
    return ret

code()
x=datetime.datetime.now()  # 特定格式的当前时间
print(x)